Locking does not occur in ActiveJDBC. ActiveJDBC models are completely disconnected from the database, as AJ does not even has a notion of a session.
Optimistic locking is supported: http://javalite.io/optimistic_locking
Pessimistic locking is a way to lock a set of rows for some time so that one user only can update them. Please, see CONCUR_UPDATABLE for more information. Generally speaking, pessimistic locking is more trouble than it is worth. ActiveJDBC does not support it. You will have to use plain JDBC for that.
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